The present disclosure relates generally to backlight units used as an illumination source for a display device and, more specifically, to techniques for enhancing the resolution of luminance levels provided by a backlight unit.
This section is intended to introduce the reader to various aspects of art that may be related to various aspects of the present techniques, which are described and/or claimed below. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present disclosure. Accordingly, it should be understood that these statements are to be read in this light, and not as admissions of prior art.
Electronic devices increasingly include display devices to provide visual feedback as part of a user interface. For instance, display devices may display various images associated with the operation of the electronic device, including photographic images, video, images representative of text (e.g., a document, a webpage, or an e-mail, etc.), as well as images associated with a graphical user interface (e.g., icons, windows, screens, etc.) of the electronic device. As may be appreciated, display devices may be employed in a wide variety of electronic devices, such as desktop computer systems, laptop computers, as well as handheld computing devices, such as cellular telephones and portable media players. In particular, liquid crystal display (LCD) panels have become increasingly popular for use in such display devices, due at least in part to their light weight and thin profile, as well as the relatively low amount of power required for operation of the pixels within the LCD panel.
However, because an LCD does not emit or produce light on its own, a backlight unit is typically provided in conjunction with the LCD panel as part of the display device in order to produce a visible image. A backlight unit typically provides backlight illumination by supplying light emitted from a light source to the LCD panel. For instance, the light sources may include cold cathode fluorescent lamps (CCFLs) or light emitting diodes (LEDs). For backlight units that utilize LED light sources, one or more groupings of LEDs may be switched such that they are periodically activated and deactivated to reduce power consumption, but a frequency that is great enough to where the light source appears to be constantly on to the human eye.
One technique for driving LED sources in this manner includes using pulse width modulation (PWM) signals, where the duty cycle of the PWM signal represents how bright the light output will appear to the human eye. However, since the duty cycle of the PWM signal is generally determined using a function having a limited bit-resolution (e.g., 10 bits), the change in luminance between each PWM controlled luminance step may be noticeable to the human eye. Thus, when adjusting the brightness of a display, the individual transition between each luminance level may be perceivable by a viewer, which may be distracting and may negatively affect the user experience.